Metals are used as catalysts in a diversity of chemical processes. Ideally, it is desired to have such metals in as finally dispersed a state as possible so as to maximize catalytic activity. When metals are used in their most highly dispersed state, a batch-type process is often employed. Removal of the catalyst in subsequent processing is disadvantageous because of attending loss of metal and the necessity for costly separation stage. Therefore, metals commonly are deposited on an appropriate supporting medium in a more discrete fashion, for example, as extrusions, tablets, pellets, etc. Utilization of the metal in such a form permits continuous process, but it is found that the metal is not in such a finally dispersed state as otherwise possible. Furthermore, transport phenomena become important because much of the metal is in the interior of the supporting medium and not on its surface.
For such reasons it is highly desirable to have a metal, when used as a catalyst, in a highly dispersed state largely on the surface of the supporting medium, but with the medium of such a nature that it has the properties necessary for its use in a continuous process.